Field-magnet winding for dynamo-electric machines.



I B. G. LAMMB. FIELD MAGNET WINDING FOR DYNAMIC ELECTRIC MACHINES.

APPLICATION FILED JAN. 26, 1910.

' Patented May 5, 1914.

WITNESSES: INVENTOR 2 Z g 6 l I v ATTORNEY UNITED sTArns PATENT, OFFICE.

, BENJAMIN G. LAMME, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTING- 'HOUSE ELECTRIC AND MANUFACTURING SYLVAN 1A..

COMPANY, A CORPORATION OF PENN- FIELD-MAGNET WINDING FOR DYNAMO-ELECTRIC MACHINES.

new and useful Improvement in Field-Magnet \Vindings for Dynamo Electric Machines, of which the following'isa specifica-.

tion,

M invention relates to' dynamo-electric mac ine's, and it has special reference to single hase motors of the commutator type.

Tiie object of my invention is to provide a simple and symmetrical field magnet winding which shall be so arranged, and traversed by such currents as to produce, not only the usual fieldmagnet poles, but also intermediate or commutating poles, whereby thenecessity for an independent compensating winding is obviated.

' Small single phase motors of the commutator type have usually been provided with compensating windings on the field magnet or primary member in order'to prevent cross magnetization and to neutralize the arma ture self induction. A winding of this character is, however, relatively expensive, particula'rly for machines of small capacity and,

consequently, it is my present aim to prevent the cross magnetization and to providea motor having reasonably good characteristics without using any compensating wind- Thepole face in a single base motor covers: a certain section of t e armature winding and the ampere turns under this pole face produce a cross magnetization or cross flux'through the pole face, the flux entering at one edge of the pole and leaving at the other. Since this cross flux is alternating, it produces self induction in the armature winding and, consequently, has an injurious effect upon the power factor and efliciency of the machine. The cross flux in question will depend upon the number of armature ampere turn-scovered by the pole face and, consequently, if .the number of poles is doubled without changing the number of armature turns, the cross flux per pole will be approximately halved and the self induction will be greatly reduced. It is not generally feasible, however, to increase the number of poles in order to cut' down the Specification of Letters Patent. A Application filed January 26, 1910. Serial No. 540,187.

Patented May 5, 1914.

amount of cross flux when the usual parallel armature windin is employed because increasingthe num er of poles decreases the number of conductors in series in the armature winding and also decreases the induct on pler pole. 'This is evident, since decreasmg t e induction per pole and the number of conductors in series greatly reduces the generated armature voltage or the counter-electromotive force, so that, for agiven torque, the current handled at the commutator will be very much increased. On the other hand, if the number of poles isincreased when the well-known two-circuit or series type of armature winding is employed, the flux per pole is proportionately diminished, but, in this case, the generated armature voltage or the counter-electromotive force remains the same, since this voltage is dependent upon the armature speed, in-revolutions, the flux er pole, the number of poles and the numer of conductors in series, and, therefore, for a given armature speed, if the number of poles is increased and the induction per pole 1S proportionately decreased, the generated voltage remains the same. However, by increasing the number of poles, the number of armature turns under each pole is diminished and, consequently, the armature flux is proportionately diminished. The cross flux, in turn, acts upon a smaller number of arma- 'ture conductors so that the self induct-ion per pole is very materially reduced and the total" armature self-induction, due a) cross magnetization, is considerably diminished. From the foregoing, it is evident that by using a two-circuit or series type of armature winding and sufiiciently increasing the number of poles, the armature self induction, due to cross magnetization, may be so reduced as to render a neutralizing or compensating winding unnecessary. This arrangement has the disadvantage of increasing the so called voltage of reversal in the armature coils under the commutator brushes, since, with a series type of winding, the number of conductors in series between any two ad'acent commutator bars is equal to the num er of poles. The, commutating characteristics would usually be very poor if the number of poles were increased sufii ciently to materially reduce the armature self induction. Experience has shown that it is possible to materially reduce the voltage of reversal "by the use of commutating poles for the purpose of overcoming the approximately 90 the armaelectro-motive force.

local magnetic field produced by ture coils, which are being reversed.

According to my present invention, 1 providea simple field magnet winding and excite it in such manner as to produce the usual main magnetic poles and intermediate or commutating poles which are out-ofphase with the main poles. By. utilizing this field winding with av two-circuit or series =type of armature winding, I provide a satisfactory motor of the commutator type for prising two parts 6 and f source tap 17 sponding coils of both operation by single phase currents, which is much simpler and less expensive than the motors ofthis type which have heretofore been constructed; 1

The single figure of the accompanying drawing is a diagrammatic viewshowing developments of single phase motor windings embodying my invention, and the external circuit connections theref0r.- 1 7 Referring to the drawing, an armature winding (1!, of a two-circuit or series type, having itscoils Z) connectedto the commutatorbars c in the usual manner, is associated with a field magnet winding (Z comwhich are, for convenience in illustration, shown by-light and heavy lines, respectively. The two parts a and f are similar to each other, but are spaced apart slightly so that the correparts surround each of the main'poles 1, 2, 3, 1, 5 and 6, and so that auxiliary or commute-tin poles 7, 8, 9', 10, 11 and 12 are produced tween corresponding conductors of the two parts and are surrounded by noncorresponding coils of the two parts. Two c0rre5pondin'g terminals of the two parts are joined together at 13 and the other corresponding terminals of'the parts are respectively con? nectedto the terminals 14 and 15 of a transformer winding 16. An intermediate point-preferably the middle point-in the transformer winding 16 is connected to a of alternating current energy, such as in a transformer 18, which is connected'across the circuit of the single phase generator 19. The point 18 is connected, by conductor 20, to a commutator brush 21, and a commutator brush 22 is connected, by means of a conductor 22, to the side of the supply circuit which is opposite that of the connection 17. Energy is consequently supplied vto the motor in series and traverses the twoparts of the main field magnetwinding inparallel.

A primary winding 23 is supplied with energy from intermediate taps 2 1 and 25 of the transformer 18 and is in inductive relation to the winding 16, so that a current is induced therein and traverses the two parts of the field magnet winding in series. Since I the energy supplied to this circuit is largely inductive the magnetizing current will lag behind tne transformer l fore out-of-phase with the main field excit ing current and it traverses the two parts of the winding in such manner that magnetic l poles are produced at 7, 8, 9, 10, 11 and 12, i which are out-of-phasdwith themain magnetic poles.

In order tomake the truth of the above statement apparent, the main poles land 2 and the intermediate pole 8 may be considered: Assuming that, at a given instant, the current is flowing from conductor 17 oppo sitely through two halves of the transformer winding 16; throughconductors 14L and 15, and through-the parts 6 and f of the mai winding, to the point 13; the currents will flow through the conductors between the poles 1 and 8, and 8 and 2m the direction of the arrow 3 and the currents will flow in the conductors between the poles 2 and 9, and 9 and 3 in the direction of the arrow 02. It is, therefore, apparent that both parts of the main field winding are active in producing the main magnetic poles. By reason of the transformer action between the windings 23 and 16, a current may be assumed to be flowing at the same instant from terminal 14 of the winding. 16 through the part 6 of'the main winding to the terminal 13 and in the opposite direction from this point through the part 1 to the terminal 15 of the transformer. This out-of-phase current traverses the conductors between the poles 1 and 8 in the direction of the arrow 1 and traverses the conductors between the poles 2 and9 in the direction of the arrow 00, but the out-ofphase current traverses the conductors betweenthe poles 8 and 2, in the direction of the arrow w, and traverses the conductors between the poles 9 and 3, in the direction of the arrow y. Therefore, the out-of-phase current produces an out-of-phase magnetic pole at 8 which serves as a commutating pole in the operation of the machine.

Considerable saving in expense is effected by avoiding the necessity of an independent winding for producing commutating poles or for neutralizing the armature self induction'and it is evident that my invention may be applied to various types of dynamo-electric machines.

I claim as m invention:

1. The comb nation with a dynamo-electric machine having a multipolar series or two circuit armature winding to reduce the armature self-induction due to cross magnetization and a multipolar field magnet havin awinding composed of two similar space parts, of means for supplying current to the two parts in parallel for producing main magnetic poles and means for supplying out-of-phase current to the two parts in series for producing auxiliary or commutating magnetic poles to reduce the voltage of reversal.

2. The combination with a multipolar series or two circuit armature winding, a commutator connected to the armature coils, and brushes engaging the commutator bars, of a multip'olar field magnet having a winding composed of two parts that are spaced apart and are joined atone end to one of the commutator brushes and a transformer winding by which the parts of the field magnet winding are joined at their opposite ends, of a source of alternating current.

energg' connected to the middle point of the trans ormer and to the commutator brush of opposite polarity, and means for inducing out-of-phase current in thetransformer,

BENJ. e. LAMME.

" Witnesses: i

E. LIvmosToNn, B. B. Hmns. 

